Not everyone gets time to do voluntary work. Others choose to take on voluntary efforts irrespective of time commitments.
Voluntary work is a blessing, rewarding, and fulfilling. Rewarding because of the skills one acquires, like interpersonal skills, leadership skills, and time management skills. Fulfilling in the sense that you are doing something that you want to do, not have to do. Finally, and most importantly, the satisfaction you get for making a positive difference in the lives of others.
There are times when voluntary work gets frustrating, especially when there are inefficiencies or more likely when your ego gets in the way. However, when you take voluntary work as a blessing and a privilege, nothing frustrates you because you have a goal larger than self!